CN114639931B - Reflection-free microstrip line band-pass filter structure - Google Patents
Reflection-free microstrip line band-pass filter structure Download PDFInfo
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- CN114639931B CN114639931B CN202210221482.8A CN202210221482A CN114639931B CN 114639931 B CN114639931 B CN 114639931B CN 202210221482 A CN202210221482 A CN 202210221482A CN 114639931 B CN114639931 B CN 114639931B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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Abstract
The invention discloses a reflection-free microstrip line band-pass filter structure, which comprises a dielectric substrate, wherein the top surface of the dielectric substrate is provided with a microstrip line structure, and the bottom surface of the dielectric substrate is provided with a metal ground structure. The microstrip line structure comprises a broadband band-pass filtering part and a broadband band-stop filtering part, wherein the microstrip line is connected with a microstrip line by adopting a short circuit of a terminal of a coupling line, the microstrip line is grounded again to form the broadband band-stop filter part, out-of-band reflected signals are received, and the out-of-band reflected signals are absorbed by loading absorption resistors between the coupling line and the microstrip line and between the microstrip line and a grounding structure respectively. The structure of the invention has the advantages of planarization, simple structure, easy integration, wide frequency band, band-pass performance, no reflection out of band and the like, and is an important radio frequency passive device which is favorable for improving the stability of a radio frequency system and the communication performance of a radio frequency front end.
Description
Technical Field
The invention relates to a reflection-free microstrip line band-pass filter structure.
Background
Modern wireless communication systems, such as 5G communication, are intended to provide users with a variety of ultra-high data rate services in a fully dynamic radio access scenario. Therefore, in order to develop a complex radio frequency front end of a mobile terminal, more complex microwave circuits and sub-branch systems need to be considered. However, the diversified and multi-scenario wireless communication needs all have respective communication standards. Thus, signal interference can occur between different wireless devices, which presents a significant challenge to the radio frequency circuitry. Bandpass filters are commonly used in various microwave radio frequency systems to achieve the adaptive signal preselection functions required for these radio frequency systems to flexibly alleviate external frequency and power sensitive interference problems that may occur due to increasingly crowded electromagnetic environments. With the continuous development of wireless systems, in order to reduce the interference of signals as much as possible, the wider and better the stopband of the filter is required, the higher and better the stopband suppression degree is, so that the interference from signals in each frequency band can be reduced to the greatest extent.
It is well known that most microwave filter topologies obtain their transfer function by a frequency selective reflection process of the rf signal energy at their input. However, these signal power reflections in the stop band range can adversely affect the performance of the overall rf system, and can even severely reduce the overall linearity and efficiency of the rf system. In this case, the advent of absorptive/non-reflective microwave filters in recent years has been well addressed to suppress spurious signal levels in mixing systems, and has attracted considerable attention in industry and academia. Unlike conventional filters that reflect the stop band signal back to the input port, non-reflective filters absorb the stop band, greatly reducing the signal level of the reflection source. Thus, the reflectionless filter plays an important role in improving the performance of the mixing system and the high gain amplifier. The existing band-pass and band-stop filters generally have reflection signals outside the working frequency band, and a small number of filters with no reflection often have the problems of narrow bandwidth, complex structure, poor absorption effect and the like.
Disclosure of Invention
The invention aims to: aiming at the prior art, the reflection-free microstrip line band-pass filter structure has the advantages of wide frequency band, simple structure and good absorption effect.
The technical scheme is as follows: the reflection-free microstrip line band-pass filter structure comprises a dielectric substrate, wherein a microstrip line structure is arranged on the top surface of the dielectric substrate, and a metal ground structure is arranged on the bottom surface of the dielectric substrate; wherein the microstrip line structure comprises a broadband band-pass filtering part, a broadband band-stop filtering part, a microstrip line ML2 as an input port and a microstrip line ML3 as an output port;
the broadband band-pass filtering part comprises a coupling microstrip line MCL1, a coupling microstrip line MCL2 and a microstrip line ML1; the right end of the microstrip line ML2 is connected with the left end of the lower microstrip line in the coupling microstrip line MCL1, the left end of the microstrip line ML3 is connected with the right end of the lower microstrip line in the coupling microstrip line MCL2, and one end of the microstrip line ML1 is simultaneously connected with the right end of the upper microstrip line in the coupling microstrip line MCL1 and the left end of the upper microstrip line in the coupling microstrip line MCL 2;
the broadband band-stop filtering part comprises a resistor R1, a coupling microstrip line MCL3, a microstrip line ML4, a resistor R2 and a grounding structure Patch; the coupling microstrip line MCL3 is transversely arranged below the coupling microstrip line MCL1, the left end side surface of the upper side microstrip line in the coupling microstrip line MCL3 is connected with the right end side surface of the microstrip line ML2 through a resistor R1, the left end of the microstrip line ML4 is in short circuit with the right end of the coupling microstrip line MCL3, and the right end of the microstrip line ML4 is connected with the grounding structure Patch through the resistor R2.
Further, the length L1, the center frequency f of the coupling microstrip line MCL1 0 And the relative dielectric constant epsilon of the dielectric substrate r The relation between them is satisfied:wherein c 0 Is the speed of light; the length L1 of the coupling microstrip line MCL1, the length L2 of the coupling microstrip line MCL2, the length L6 of the coupling microstrip line MCL3, the length L3 of the microstrip line ML1, and the length L7 of the microstrip line ML4 satisfy: l1=l2=l6=l7= 0.5L3.
Further, the distance w8 between the coupling microstrip line MCL1 and the coupling microstrip line MCL2 and the line width w3 of the microstrip line ML1 satisfy: 0< w8< w3.
The beneficial effects are that: the reflection-free microstrip line band-pass filter structure adopts the coupling line terminal short circuit to be connected with the microstrip line, the microstrip line is grounded again to form a broadband band-stop filter part, the reflection signals outside the band are received, and the absorption resistors are respectively loaded between the coupling line and the microstrip line and between the microstrip line and the grounding structure to absorb the reflection signals outside the band. The structure of the invention has the advantages of planarization, simple structure, easy integration, wide frequency band, band-pass performance, no reflection out of band and the like, and is an important radio frequency passive device which is favorable for improving the stability of a radio frequency system and the communication performance of a radio frequency front end.
Drawings
FIG. 1 is a top view of a wideband reflection-free microstrip line bandpass filter according to the invention;
FIG. 2 is a diagram showing the structural dimensions of a wideband reflection-free microstrip band-pass filter according to the present invention;
FIG. 3 is a schematic diagram of a wideband reflection-free microstrip band-pass filter according to the present invention;
FIG. 4 shows the reflection coefficient S in the embodiment 11 And transmission coefficient S 21 Graph of frequency response.
Detailed Description
The invention is further explained below with reference to the drawings.
The reflection-free microstrip line band-pass filter structure suitable for the radio frequency front-end system comprises a dielectric substrate MS, wherein the top surface of the dielectric substrate MS is provided with a microstrip line structure PEC, the bottom surface of the dielectric substrate MS is provided with a metal ground structure PEC, and a metalized through hole VH is arranged in the dielectric substrate MS. The microstrip line structure comprises a broadband band-pass filtering part, a broadband band-stop filtering part, a microstrip line ML2 as an input port and a microstrip line ML3 as an output port.
The broadband bandpass filtering part comprises a coupling microstrip line MCL1, a coupling microstrip line MCL2 and a microstrip line ML1. The coupling microstrip line MCL1 and the coupling microstrip line MCL2 are transversely arranged in the same row at intervals, the right end of the microstrip line ML2 is connected with the left end of the lower microstrip line in the coupling microstrip line MCL1, and the left end of the microstrip line ML3 is connected with the right end of the lower microstrip line in the coupling microstrip line MCL 2; one end of the microstrip line ML1 is simultaneously connected with the right end of the upper microstrip line in the coupling microstrip line MCL1 and the left end of the upper microstrip line in the coupling microstrip line MCL2, so that the overall structure is compact, and the microstrip line ML1 is subjected to bending processing.
The broadband band-stop filtering part comprises an absorption branch circuit consisting of a resistor R1, a coupling microstrip line MCL3, a microstrip line ML4, a resistor R2 and a grounding structure Patch. Specifically, the coupling microstrip line MCL3 is transversely disposed below the coupling microstrip line MCL1, the left end side surface of the upper side microstrip line in the coupling microstrip line MCL3 is connected with the right end side surface of the microstrip line ML2 through a resistor R1, the left end of the microstrip line ML4 shorts the right end of the coupling microstrip line MCL3, the right end of the microstrip line ML4 is connected with the grounding structure Patch through the resistor R2, and the grounding structure Patch is formed by a square Patch and is connected with the metal grounding structure PEC through a metallized through hole VH.
The microwave radio frequency signal is fed in through the left end of the microstrip line ML2, namely the port 1, the microwave signal in the passband is transmitted into the coupling microstrip line MCL1 through the microstrip line ML2, the signal is transmitted to the microstrip line ML3 through the microstrip line ML1 and the coupling microstrip line MCL2, and is output through the right end of the microstrip line ML3, namely the port 2. The coupling microstrip line MCL1, the coupling microstrip line MCL2 and the open-circuit branch microstrip line ML1 jointly generate band-pass filter response, realize two transmission zeros and enhance the filtering performance. The reflection signals outside the pass band are transmitted through the absorption branch circuit, and as the resistance R1 and the resistance R2 are introduced into the absorption branch circuit to serve as absorption resistors, the reflection signals outside the pass band are absorbed by the absorption resistors, and finally the broadband reflection-free band-pass filter is realized.
As shown in fig. 2, the microstrip line ML2 has a length L4 and a line width w4; the length of the coupling microstrip line MCL1 is L1, the line width is w1, and the interval is s1; the length of the coupling microstrip line MCL2 is L2, the line width is w2, the spacing is s2, and the spacing between the coupling microstrip line MCL1 and the coupling microstrip line MCL2 is w8; the line width of the microstrip line ML1 is w3, and the length is L3; the length of the coupling microstrip line MCL3 is L6, the line width is w6, and the interval is s6; the length of the microstrip line ML4 is L7, and the width is w7; the diameter of the metallized via VH is d.
Wherein the length L1 and the center frequency f of the coupling microstrip line MCL1 0 And the relative dielectric constant epsilon of the dielectric substrate r The following are satisfied:wherein c 0 Is the speed of light; length L2, center frequency f of coupling microstrip line MCL2 0 And the relative dielectric constant epsilon of the dielectric substrate r The following are satisfied: />Length L6, center frequency f of coupling microstrip line MCL3 0 And the relative dielectric constant epsilon of the dielectric substrate r The following are satisfied: />Length L5, center frequency f of microstrip line ML3 0 And the relative dielectric constant epsilon of the dielectric substrate r The following are satisfied: />The length L7 and the center frequency f of the microstrip line ML4 0 And the relative dielectric constant epsilon of the dielectric substrate r The following are satisfied: />And the length L1 of the coupling microstrip line MCL1, the length L2 of the coupling microstrip line MCL2, the length L6 of the coupling microstrip line MCL3, the length L3 of the microstrip line ML1, and the length L7 of the microstrip line ML4 satisfy: l1=l2=l6=l7= 0.5L3. The distance w8 between the coupling microstrip line MCL1 and the coupling microstrip line MCL2 and the line width w3 of the microstrip line ML1 satisfy: 0<w8<w3。
In order to better illustrate the technical effect of the invention, the embodiment designs a broadband reflection-free microstrip line band-pass filter with the center frequency of 2GHz, and performs optimization simulation verification on the filter, and the structure parameters are as follows: microstrip line ML2: w4=3.51 mm, l4=22.87 mm; coupling microstrip line MCL1: w1=0.3 mm, s1=0.6 mm, l1=23 mm; coupling microstrip line MCL2: w2=0.85 mm, s2=0.15 mm, l2=23 mm; microstrip line ML1: w3=3.51 mm, l3=47 mm; microstrip line ML3: w5=3.51 mm, l5=22.87 mm; coupling microstrip line MCL3: w6=2.3 mm, s6=0.18 mm, l6=24 mm; microstrip line ML4: w7=5.8 mm, l7=22.4 mm; resistance r1=20Ω; resistor r2=30Ω; the dielectric substrate is made of RO4003C plate, the thickness h=1.524 mm, and the dielectric relative permittivity is epsilon r =3.38. Slow wave structures of other frequency bands may be available by scaling on the slow wave structure in the present embodiment.
FIG. 4 is the present embodimentExample reflectance S obtained by simulation of HFSS three-dimensional simulation software 11 And transmission coefficient S 21 Graph of frequency response. As can be seen from the figure, the reflection coefficient S is in the frequency range of 0 to 4GHz 11 Are all smaller than-11.94 dB; transmission coefficient S 21 The broadband filter shows band-pass response, the 3dB bandwidth range is 1.44-2.72 GHz, the corresponding relative bandwidth is 80%, and the broadband filter has broadband non-reflection band-pass filtering performance.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (3)
1. The reflection-free microstrip line band-pass filter structure is characterized by comprising a dielectric substrate, wherein the top surface of the dielectric substrate is provided with a microstrip line structure, and the bottom surface of the dielectric substrate is provided with a metal ground structure; wherein the microstrip line structure comprises a broadband band-pass filtering part, a broadband band-stop filtering part, a microstrip line ML2 as an input port and a microstrip line ML3 as an output port;
the broadband band-pass filtering part comprises a coupling microstrip line MCL1, a coupling microstrip line MCL2 and a microstrip line ML1; the right end of the microstrip line ML2 is connected with the left end of the lower microstrip line in the coupling microstrip line MCL1, the left end of the microstrip line ML3 is connected with the right end of the lower microstrip line in the coupling microstrip line MCL2, and one end of the microstrip line ML1 is simultaneously connected with the right end of the upper microstrip line in the coupling microstrip line MCL1 and the left end of the upper microstrip line in the coupling microstrip line MCL 2;
the broadband band-stop filtering part comprises a resistor R1, a coupling microstrip line MCL3, a microstrip line ML4, a resistor R2 and a grounding structure Patch; the coupling microstrip line MCL3 is transversely arranged below the coupling microstrip line MCL1, the left end side surface of the upper side microstrip line in the coupling microstrip line MCL3 is connected with the right end side surface of the microstrip line ML2 through a resistor R1, the left end of the microstrip line ML4 is in short circuit with the right end of the coupling microstrip line MCL3, and the right end of the microstrip line ML4 is connected with the grounding structure Patch through the resistor R2.
2. The reflection-free microstrip line bandpass filter structure according to claim 1, wherein the coupling microstrip line MCL1 has a length L1 and a center frequency f 0 And the relative dielectric constant epsilon of the dielectric substrate r The relation between them is satisfied:wherein c 0 Is the speed of light; the length L1 of the coupling microstrip line MCL1, the length L2 of the coupling microstrip line MCL2, the length L6 of the coupling microstrip line MCL3, the length L3 of the microstrip line ML1, and the length L7 of the microstrip line ML4 satisfy: l1=l2=l6=l7= 0.5L3.
3. The reflection-free microstrip line bandpass filter structure according to claim 1, wherein a spacing w8 between the coupling microstrip line MCL1 and the coupling microstrip line MCL2 and a line width w3 of the microstrip line ML1 satisfy: 0< w8< w3.
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| CN202210221482.8A CN114639931B (en) | 2022-03-09 | 2022-03-09 | Reflection-free microstrip line band-pass filter structure |
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| CN114639931B true CN114639931B (en) | 2023-07-18 |
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| CN213124692U (en) * | 2020-11-10 | 2021-05-04 | 成都拓芯电子科技有限公司 | Signal filtering device for vibration sensor |
| CN112909461A (en) * | 2021-01-25 | 2021-06-04 | 北京邮电大学 | Complementary duplex structure full-band absorption dual-frequency band-pass filter |
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2022
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| CN105529515A (en) * | 2016-01-28 | 2016-04-27 | 华南理工大学 | Adjustable bandpass-bandstop filter based on loading on open circuit branch |
| CN108493566A (en) * | 2018-04-18 | 2018-09-04 | 西安电子科技大学 | A kind of restructural filtering type power splitter of Wide stop bands based on SIR and DGS structures |
| CN213124692U (en) * | 2020-11-10 | 2021-05-04 | 成都拓芯电子科技有限公司 | Signal filtering device for vibration sensor |
| CN112909461A (en) * | 2021-01-25 | 2021-06-04 | 北京邮电大学 | Complementary duplex structure full-band absorption dual-frequency band-pass filter |
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